What is additive property of Appenders, and how is it enabled and disabled?
A log request that is enabled is logged by appenders of the current logger, and also by all the appenders up the hierchachy. Thus, we say Appenders are additive for a logger hierchchy. To disable the additive property we set the additive property of the logger to flase; it is true by default. Any logger in the hierarchy could decide whether to inherit loggers from its parent by setting this flag.
